1. Field of the Invention
The present invention relates generally to a semiconductor process, a planar field effect transistor and a fin-shaped field effect transistor, and more specifically to a semiconductor process, a planar field effect transistor and a fin-shaped field effect transistor including extension parts enlarging gate channels.
2. Description of the Prior Art
Metal-Oxide-Semiconductors (MOS) transistors are widely used transistors. Current transistor includes a gate, a source and a drain. The source and the drain are respectively located in a substrate, and the gate is located on the substrate between the drain and the source, to control the switching of currents in a gate channel below the gate and sandwiched by the source and the drain. Generally, transistors may be divided into planar transistors and non-planar transistors.
With increasing miniaturization of semiconductor devices, various non-planar transistors such as multi-gate MOSFET devices have been developed. The multi-gate MOSFET is advantageous for the following reasons. First, manufacturing processes of multi-gate MOSFET devices can be integrated into traditional logic device processes, and thus are more compatible. In addition, since the three-dimensional structure of the multi-gate MOSFET increases the overlapping area between the gate and the substrate, the channel region is controlled more effectively. This therefore reduces drain-induced barrier lowering (DIBL) effect and short channel effect. Moreover, the channel region is longer for the same gate length. Therefore, the current between the source and the drain is increased.
A multi-gate MOSFET may include a fin structure, and the gate is disposed over the fin structure to form the multi-gate MOSFET different from a planar transistor. A height of the fin structure and a width of the gate disposed over the fin structure affect the width and the length of the gate channel of the multi-gate MOSFET.
As the integration of integrated circuits enhances, leading to property limitations such as material and process limitations, new transistors such as planar or non-planar transistors are developed in the industry to increase density of transistors on a substrate as well as current between sources and drains.